A light emitting diode (LED) is normally a light emitting PN junction diode composed of III-V or II-VI semiconductor compounds, such as GaAs, GaP, AlxGa1-xAs, ZnSe, etc. When a forward bias is applied to the LED, the electrons in the N-type semiconductor combines with the holes in the P-type semiconductor. Since the electrons transition to a lower energy level, the superfluous energy is converted to photons, thereby emitting light. Since the electrons and the holes are continuously provided to the N-type and the P-type semiconductors from the current of the power source, the light emission process due to the electron-hole pair recombination persists, and the LED generates light continuously. For this reason, in contrast to a conventional light bulb, which generates light from thermal energy, the basic principle of light emission from the LED is due to the energy level transition of electrons. Therefore, the LED is a cold light emitting device, which is advantageous in that the LED generates less heat and consumes less power. In addition, the LED is more durable, faster in response, smaller in size and weight than the conventional light bulb.
In the range of visible light, the LED enters into many different marketplaces, such as the consumer electronic products, the information technology products, the communication products, and the back light source, by replacing the conventional small white light bulb. Later, the development and commercialization of high luminescence products have further extended the application of LED to the brake light of vehicles and the outdoor display boards. In recent years, high luminescence white LED products made of InGaN material have proven their success, which will indubitably revolutionize the LED applications.
The LED as an indicator is often installed on the circuit board of any apparatus. The apparatus comprises a housing, wherein a light guide pillar is disposed between the surface of the housing and the LED indicator. Conventional light guide pillar comprises a base, and at least a light guide pillar disposed on the base extending outward. One end of the light guide pillars is connected to the LED, while the other end of the light guide pillars is connected to the panel of an electronic apparatus. The light emitted from the LED is displayed on the panel by guiding through the light guide pillar. Furthermore, a first fastening member is disposed on one side of the base extending outward, while a second fastening member is disposed on another side of the base extended inward to incorporate with the first fastening member. The first fastening member of a base is incorporated with the second fastening member of another base such that the two bases are connected together. In this manner, the user can combine a number of light guide pillars via the bases thereof according to the number of LED that is required.
However, regardless of whether the light guide pillars emit light in a single direction or in a multiple of directions, the user will experience inhomogeneous or leaking luminescence when looking at the light guide pillar, which renders the usage very inconvenient. In addition, different messages are often represented and indicated by different colors of LEDs. Since the separation between the LEDs is very close to each other, the emitted light often interferes with each other, resulting in color mixing. For this reason, it is difficult for users to clearly identify the message that the indicator is displaying when the indicator is displaying two or more colors at the same time. Some possible solutions are available in the art. Among them, one possible solution is to employ a light blocking rib to hinder the light transmission. However, the effect of this solution is not significant. Another solution is to increase the separation between LEDs to prevent light intervention. However, this solution requires the compliance of the circuit board and the appearance. Moreover, such light intervention still remains when the luminescence of the LEDs is too high. Therefore, the problems of the conventional light guide pillars are not yet solved.